Fuel Flexibility in Co-Generation Applications · • Siemens SGT-200 high hydrogen fuel capability expanded to cover COG • Gas cleaning prior to turbine to remove or reduce levels

Restricted © Siemens AG 2015 All rights reserved. Answers for energy.

Fuel Flexibility in Co-Generation

Applications

DistribuGen Conference & Trade Show for Cogeneration/CHP 2015

Restricted © Siemens AG 2015 All rights reserved.

2015-04-07 Page 2 DE/DistribuGen

Natural Gas: the Fuel of Choice ?

What can be done if natural gas is not available ?

• Temporary interruption • Liquid fuel as back-up

• Long-term interruption or non-availability of gas

• Consider alternative fuels

• Refined Liquid Fuels • Diesel, Kerosene, IF and HFO

• Crude oil and refinery residues

• Volatile liquid fuels • NGLs, LPG, Naphtha, ethanol

• Alternative gas fuels • Biogases, process off-gases

• All these alternatives are potential fuels for Gas Turbines • Project economics may be affected but may be preferable to

complete loss of production Gas Turbine fuel test facilities



Fuel Types / Ranges

Fuel Ranges

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90

Lower Heating Value [MJ/kg]

Wo

bb

e I

nd

ex

[M

J/N

m3]

Examples of Fuels assessed by Siemens

The bulk of fuels typical of natural gases.

Fuel types to lower LH corner are typical

of increased dilution from CO2 or N2 species



Fuel Types / Ranges

Consider the influence of diluents such as Carbon Dioxide and/or Nitrogen

• As diluent amount increases the

energy content of the fuel

decreases, therefore more

“weakened” fuel flow required

• Applying a rigorous

development process, as will be

described in the next slide the

capability to burn such fuels

was released

• This recognised the physical

limitations on supply pressure

and combustor pressure drop

(more on this later)



Fuel Types / Ranges

Understanding Product Capability Development Process

Combustion Development Process ► Analytical methods underpin

practical tests

► High pressure combustion

testing applied to can type

combustion hardware

► Design or geometry change

rapidly accommodated

Spray tests

injector analysis

High pressure

Combustion tests

proving design

Sprays in situ

oil/aerodynamics

interaction

DLE Enhancement

spray-rig work - momentum-flux ratio scaling

dry-oil

- Add text to be highlighted-- Add text to be highlighted-

standard profiled

Water flow tests

aerodynamic

analysis

Atmospheric

combustion

test Ignition tests,

study

combustion

modes

Engine

performance

Models

CFD, FEA

0D, 1D

Models underpin the

development process

Models evolve through

the development

process



Fuel Types / Ranges – Combustion Rig Facilities

Combustion Facilities

High Pressure Combustion Rigs

Allows combustion testing at full

engine temperature and pressure

Facility covers all current product

range

Gas Fuel Mixing Facility

Ability to mix fuels to meet full WI

range

Covers range 15 – 65+MJ/m3 WI

Alternative

liquid fuel

storage

CO2 & N2

Storage H2 & CO

container

s

Butane/Propa

ne Storage

vessel



Fuel Types / Ranges

Impact of fuel heating value

5 10 15 20 25 30 35 40 45 50 55 60 65

Temperature Corrected Wobbe Index

Low Calorrfic Value (LCV)

Medium Calorrfic Value (MCV)

Pipeline Natural GasHigh Calorific Value (HCV)

Standard range for supply pressure or pressure drop

across burner

Su

pp

ly P

ress

ure

Pre

ssu

re d

rop

acr

oss

bu

rne

r

StandardBurner

Burner BBurner A

Pressure drop

across combustor



Alternative Gas Fuels

University of New Hampshire (UNH), USA

• Tri-generation plant provides power, heat and cooling

to University campus

• Low emissions, 15ppm NOx, requirement • Initial operation on natural gas with diesel fuel as

back-up

• Availability of landfill gas from nearby source as low

cost fuel

• WI range to wide to consider common

configuration

• LFG processing required

• Gas fuel system able to operate on processed landfill

gas as well as natural gas

• WI control 32MJ/Nm3 acceptable

• Variable composition: natural gas mixed with landfill

gas to boost heating value

• PLG of insufficient quality or quantity

https://132.177.103.142/RSViewWeb/default.htm

Siemens SGT-300 tri-fuel DLE gas

turbine






Intelligent Fuel Control for Low NOx

emissions

• Developed for UNH

• Variable fuel composition sometimes

caused emissions limit to be exceeded

• Intelligent control developed to adjust

pilot fuel schedule to produce minimum

NOx

• Demonstrated ability to meet NOx limits

despite variations in fuel composition

• Released and available across product

range

Histogram of NOx emissions over 2 months, 1 year apart,

before and after installation of Intelligent Fuel Control



Fuel Types / Ranges

Ethanol Plant

Operation on By-product Biogas:

Composition: CH4 60mol%;

CO2 37mol%

TCWI circa 20-22MJ/m3 @ ~550C

Commissioned May 2013

Estimated Hours ~10,000hrs (Dec ‘14)

Start fuel: Biogas.



Fuel Types / Ranges

Ethane, C2H6

Ethane C2H6

Typically a by-product of the process industry, but now an increasing

“waste” from treatment of “shale Gas”

Ethane can be assessed as a gas turbine fuel in the same way as any

gaseous fuel, giving due consideration:

• Specified in suitable units (usually mol%, mol fraction, vol%)

• All contaminants are specified

Assessment defines parameters of gaseous fuel:

• Dew point (hence supply temperature)

• Calorific value; Wobbe Index, sg

• Minimum supply conditions

At minimum conditions for superheat above dew point (20degC) WI of

Ethane lies above the upper approved range limit (49MJ/m3). Elevating

supply temperature reduces the WI (Hence Temperature Corrected

Wobbe Index, or as another GT OEM refers to Modified Wobbe Index).

The next limit to apply is the fuel system limit (120DegC)



Fuel Types / Ranges

Ethane, C2H6

► In this exercise methane has been

used with ethane added until the fuel

is all ethane (range is 100% methane

to 100% ethane)

► In blue is the WI of Ethane as ethane

content is increased. This is at ISO

conditions.

► Upper limit of standard natural gas

range is 49MJ/m3 (note this is not a

“hard stop”)

► Minimum supply temperature (fuel

system operating limit) is +2.5degC

► Above about 20degC gas

temperature the fuel requires

additional heating to ensure TCWI

<49MJ/m3

► Above 80% Ethane content supply

temperature adjustments is close to

upper systems limitation, 120degC

► If no methane available then a small

amount of air can be used for dilution:

10% air results in acceptable

TCWI/supply temp



Volatile Liquid Fuels

By-products from processing or refining processes that may

offer a lower cost alternative to premium refined fuels

• Natural Gas Liquids (NGL)

• Liquified Petroleum Gas (LPG)

• Naphtha

• Ethanol

• Require changes to the liquid fuel system of Gas Turbines

• Need to ensure fuel stays as a liquid • High pressure fuel systems (typically 200 bar)

• Siemens developed a low pressure system (40 bar) for increased

safety

• Low viscosity and lubricity requires special fuel pumps

• Ethanol has only 60% energy content of diesel • Greater volumes required so larger pipework ,burner galleries etc.

Gas flaring in the Oil industry: a

potential source of NGLs and LPG

Siemens SGT-100 Low pressure

LPG / naphtha burner



Volatile Liquid Fuels

Naphtha-fuelled installation, Turkey

• Industrial customer suffering from frequent

power outages and loss of production

• Natural gas pipeline not yet constructed

• Selected naphtha as fuel for initial years of

operation until natural gas became

available

• Chose Siemens to supply a gas turbine for

a Cogeneration plant

• Improved production volumes and quality

due to reliable supplies of electricity and

process heat

Siemens SGT-100 naphtha-fuelled gas

turbine




Sometimes there are alternative gas fuels available to act

as a substitute natural gas

• By-products from industry • Coke Oven Gas; Blast Furnace Gas; Refinery Gas

• Also Syngas from gasification of biomass, coal or

Municipal or Medical Wastes

• Tend to be hydrogen-rich gases, often with carbon

monoxide

• Lower heat energy than natural gas

• Require changes to the burners, fuel and safety systems

• Increased volume flow; Hydrogen embrittlement;

Flashback risk

• Naturally-occurring methane-rich gases • Landfill gas, digester (sewage) gas, biogas

• Weak natural gases (methane + carbon dioxide)

• Minor changes to fuel systems and burners

• High volume flows

• Low pollutant emissions as suitable for DLE combustors

Cogeneration plant in a Refinery




Coke Oven Gas Installation, China

• Coke Oven Gas (COG) is a waste gas

from coke production for the steel industry

• Often just flared off as a waste product

• Free fuel

• COG mainly composed of hydrogen and

carbon monoxide

• Siemens SGT-200 high hydrogen fuel

capability expanded to cover COG

• Gas cleaning prior to turbine to remove or

reduce levels of contaminants

• Several units installed with lead units

>30,000 operating hours Siemens SGT-200 configured for

operation on Coke Oven Gas (COG),

China



Summary / Conclusions

• Natural gas is the most common fuel for

Power Generation and Cogeneration

• There are many alternative fuels that can be

used

• To cover a temporary loss of gas supply

• As a lower cost source of fuel

• Local ‘waste’ fuels can displace natural

gas

• Potentially ‘free’ or lower cost fuels

• Avoid import of natural gas by using local

resources to best ability

• Multi-fuel capability of Gas turbines allows

• Secure supply of energy

• Optimisation of economics

• Low environmental impact

Documents

Fuel Flexibility in Co-Generation Applications · • Siemens SGT-200 high hydrogen fuel capability expanded to cover COG • Gas cleaning prior to turbine to remove or reduce levels